Trimmer mechanism



March 10, 1931. SLQCUM ET AL 1,795,901

- TRIMMER MECHANISM Filed Sept. 9, 1927 5 sheets-Sheet 1 VENTORS wmys; l

Buffer! H. acurn, 7M eph A. Bous/ough &

e andB/T Burn/1am WWW March 10, 1931. B. H. SLOCUM ETAL 1,795,901.

TRIMMER MECHANISM Filed p 9 192'! 3 Sheets-Sheet 2 WITNESS 2 I INVENTORS$14! Burfan H. Slacum,

Jase 7h A. Bo -Slough & W, I 2 u YF. Jrnham ATTORNEY March 10, 1931. B.H. SLOCUM ETAL H 1,795,901

TRIMMER MECHANISM Filed Sept. 9, 1927 3 Shoots-Sheet 3 INVENTOR5WITNESSES:

Bur for! H. Slocum,

Leland E Burnbam Joseph A. boualough 8 wwaw V Patented Mar. 10,- 1931UNITED STATES PATENT OFFICE BURTON H. SLOCUM, JOSEPH A. BOUSLOUGH, ANDLELAND FLIBURNHAM, OF PITTS- IBURGH, PENNSYLVANIA, ASSIGNORS, BY MESNEASSIGNMENTS, T'O WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, ACORPORATION OF PENNSYLVANIA TRIMMER MECHANISM Application filedSeptember 9, 1927. Serial No. 218,390.

The invention "relates generally to Wheel trimming devices and moreparticularly to trimming devices for abrasive wheels'of a type suitablefor grinding purposes.

An object of our invention is to provide a device for trimming theworking surfaces of abrasive wheels to a contour suitable for grindinggear teeth and which may be util-.

ized to trim abrasive wheels for grinding gear Wheels of any desiredinvolute toot form, pitch or diameterj Heretofore trimmer mechanismsutilized for trimming the working faces of abrasive wheels to formcontours suitable for grinding gear teeth have been provided with acam'or template to guide the trimming member. The working surface of thecam was made either similar to. or identical in shape with the toothcontour it was desired to pro- 'vide, or the cam was made of an entirelydissimilar shape in order to impartthe proper motion to the trimmingmember through the medium of a compound linked mechanism. However,'thesemachines had the inherent disadvantage of indirect operation and theresulting inaccuracies introduced by loos'e-.

ness or deflections in the connecting link mechanism. Further, verycarefulworkmanship was required in the/construction and operation ofsuch machines to produce accurately trimmed abrasive wheels.

The present invention relates to a trimming device for abrasive wheelsthat.

may be utilized in grinding gear teeth, and that operates upon theprinciple of direct generation of the desired tootlf contour includingthe involute or working portion, the flank and the root fillet of thetooth upon the working faces of the abrasive wheel.

porting base, a frame member pivotally mounted on the supporting baseand a pair of spaced cylindrical "segments, of diameter The devicecomprises in general a supfrom tangential or radial displacement withrespect thereto. 1

An arcuate trimmer arm is pivotally mounted on the tangent bars andlatched to the connecting member between the bars. A trimming membersuch as a cutting diamond is adjustably mounted on the trimmer arm insuch-manner that itlies in the plane described by the bearing facesofthetangent bars. Adjusting means are provided to regulate the an angularposition of the cylindrical segments with respect to the frame member inorder to provide working faces of the proper width on the abrasive wheelto correspond with the desired tooth space of the gear wheel to beground. e V

In operation, the abrasive wheel to be trimmed is rotated at a moderatespeed and slowly fed into engagement with the trimming member. Thetangent bars are rolled on the cylindrical segments to cause the trimmermember to describe an involute curve from the base circle outward totrim the abrasive wheel to the shgpp of the working portion of a eartooth. e tangent bars may then be he (1 stationary in a predeterminedlimited position and the trimmer arm unlatched-from them and oscillatedabout itspivotal axis to cause the trimming member to describe an arefrom the base circle inward to trim the abrasive wheel to a contoursuitable for grinding the flank and root fillet of a gear tooth. Afterthe trimming operation has been completed on one sideof the abrasivewheel the frame may be turned upon the pivotal supporting base andaccurately set in'the proper position to trim the other side of thewheel to an identical contour.

- In the accompanying drawing,

Figure 1 is a plan view partially in crosssection of a wheel trimmingdevice embodying the principles of our invention;

Fig. 2 is a view in end elevation of the. trimming device of Fig. 1;

Fig. 3 is a viewin side elevation thereof. Fig. 4 is a view in sectionof a portion of 1 the trimming device taken along the line IV-IV of Fig.1 {and Fig. .5'is 'a view in section of the trimmer arm ivot mechanismtaken along the line V- of Fig. 4.

Referring to the drawing, the illustrated embodiment of the inventioncomprises a supporting base or center plate 1 that is adapted to besecured to a machine frame 2 by means of bolts 3. A center pin 4 ispressed into the base 1 and a frame or trunnion supporting member 5 isdisposed on the pin in such manner as to permit it to be set in dif- 5may be given an angular movement of sub-' stantially 180.

T slots 13 are provided in the end portions of-the frame 5 and extendparallel to each other and parallel to the center pin 4. In

T order to mount a base circle adjusting arm 17, square headed bolts 14provided with nuts 15 are mounted in the T slots 13 to serve astrunnions to receive sleeve bearings Two cylindrical segments 18 havingclamping hubs 19 and clamping bolts 21 are mounted upon the bearingsleeves 16 and clamped thereto. The cylindrical segments 18 have radiiequal to the radius of-the base circle of "the gear wheel for which anabrasive wheel is to be trimmed. The adjusting arm 17 is provided withan opening 22 in its mid porbars 31 and 32, respectively.

tion for receiving a stop pin 23. As shown in Fig. 1, the stop pin 23 isprovided with a square head 24 and is mounted in a T-slot 25 in theframe 5 in such manner that it maybe adjusted parallel to the center in4 and locked in any predetermined position by a nut 26.

Adjusting screws 27 and 28 are provided in the adjusting arm 17 forengaging the stop pin 23 to turn the adjusting arm-17 and the attachedsegments'18 about the trunnion bolts 14 for a purpose to be hereinafterde-' scribed. I a I Tangent bars 31 and32 having an integral connectingbar 33 are mounted upon the peripheries of the segments 18 in suchmanner that they are free to roll thereon and are restrained from axialdisplacement with re-' 1spect thereto by the engagement of segment anges36 in grooves 34 and 35 in the tangent bars 31 and 32 and t e segments18 are provided with alined grooves 37 j and 38 respectively in theirengaging 'faces for reins in the positions to 1 formed integral with theadjusting arm 1 The tangent ceiving wires 44 and 45 disposed to preventtangential displacement of the tangent bars with respect to the segments18.

Lugs 40 and 41 are provided upon the connecting bar 33 for receivingadjusting screws 42 and 43. 1

One end of each of the wires 44 and 45 is attached to the adjustingscrews 42 and 43, respectively. The wires 44 and 45 pass around knobs 46and 47 respectively on the connecting bar 33, through the grooves 38 and37 in the tangent bars and segments and are secured at their other endstoscrews 48 in the segments 18. 1

Other wires 51 and 52 have both their ends secured to screws 53 mountedin the segments 18 at the ends opposite to those occupied by the screws48. .The wires 51 and 52 are doubled and pass through the slots 37 and38 in the segments and tangentbars respectively in such manner that thetwo portions of them occupy positions at either side of the wires 44 and45. The looped portions of the Wires 51 and 52 are guided by suitableknobs and are passed around small pulleys 54 and 55 that are pivoted onadjusting screws 56 and 57.

Independent mechanical means are. pro vided in the form .of wheeledcarriages 61 and 62 that are mounted upon the tangent bars and supportedradially from the trunnion sleeves 16 to keep the tangent bars incont-act with the segments 18. The faces of the tangent bars 31 and 32opposite to the ments 18 are provided with central grooves 63 that areadapted to engage flanged wheels 64 of the carriages 61 and 62.

The carriages 61and '62 comprise frames 65 that are substantiallyrectangular metal blocks provided with slots at either end in which theflanged wheels 64 arepivoted upon axles 66. A plate 67 is provided uponeach carriage to serve as an anchor for the ends of wires 68 that extendfrom the carriage around small grooved pulleys 69 which are journaledupon. thebearing sleeves 16 at either side of the segment clamps 19.This arrangement provides a doubled wire extending from the carriage tothe trunnion assembly on each side of the segments 18. 7

An adjusting screw 71 having a locking llt.

nut 72 is threaded in the plate 67 and bears upon the carriage frame 65.The purpose of this adjusting screw is to lift the plate 67 from thecarriage frame 65 thereby applying tension to the wires 68 and forcingthe carriage into engagement with the tangent bar to. prevent radialdisplacement of the bar with respect to the segments 18.

Stop discs 81 are mounted upon arms 82 that are extensions of the frame5.-' The discs are mounted in the same plane with the segments 18 andserve as stops for the tangent 95. For the purpose of pivotingthe-trimmer arm 95 on the eccentric arms 86 and 87, the

openings 88 and 94 are provided with eccentric discs 91 and 93,respectively.

As shown in Figs. land 5, each of the discs- 91 is provided with twotapped holes 90 disposed at difier'ent distances from the center forreceiving a pivot pin 92. Also, each of the discs 93 is provided withtwo cone bearing surfaces 100 for receiving the end of the'pivot pin 92,in such manner that the trimmer arm 95, when mounted, is free to beturned rclative to the tangent bars 31 and 32 about an axis through thecenters of the pivot pins 92.

The purpose of mounting the pivot pins 92 in eccentric discs is torovide means for changing the position of t e pivot axis of the trimmingarm 95 with respect to the tangent bars 31 and 32. In operation, thepivot pin 92 is inserted in either of the holes 90, and

. the discs 91 and 93 are turned within the openings 88 and 94 until thedesired setting of the pivot centers is obtained. The discs 91 and 93may then be clamped in position by means of clamping screws 89. Theposit-ion of the pivot pin 92 with respect to the trimming. arm 95 maybe ascertained by means of graduations 96 that are provided on theperiphcries of the eccentric discs 93.

to the connecting bar 33 by means of the latch 98. A trimming member 101such as a cuttin diamond is mounted within the cylindrica portion 97 ofthe trimmer arm 95 by means of a threaded diamond holder 102.

The diamond holder 102 may be adjusted longitudinally of the cylindricalhandle 97 by means of its threaded engagement therewith and'may belocked in any desired position by means of lock nuts 103.

An abrasive wheel 105 to betrimmed may be rotatably mounted upon asuitable arbor 106 in such position that its axis is at rightangles tothe axis of the center pin 4 and also perpendicular to the plane passingthrough the axis of the pivot in 4 and the axis of the,

The trimmer arm 95 is provided at its center with acylin- 'drical handleportion 97 which may be latched by the segments 18 at a distance equalto of the tooth space, as measured on the base circle of the gear wheelto be ground, from the center line of axis of the pivot pin 4 when thetangent bars 31 and 32 are'in engagement with the stop discs 81.

The Wheel 105 to be trimmed may then be rotated at a moderate speed andfed into light engagement with the. trimmer member 101. The tangent bars31 and 32 together with the trimmer arm 95 and trimmer holder 102 maythen be rolled upon the peripheries of the seg ments 18 to cause thetrimming point 101 to describe an involute curve which corresponds tothe contour of a gear tooth from the base circle to the tooth tip.Successive cuts are taken from the abrasive wheel 105 in this manneruntil the desired contour is obtained.

The trimmer arm 95 may then be unlatched from the connecting bar 33 byreleasing the latch 98 and pivoted about the pivot pin 92 to cause thetrimmer member 101 to trim the periphery of the abrasive wheel to anarouate contour that is adapted for grinding the portion of a gear toothfrom the base circle to the root of the tooth, which is also known asthe flank and root fillet of the gear tooth.

When one face of the abrasive wheel 105 hasbeen trimmed to provide theproper contour, the clamping bolts 6 in the frame 5 may be released andthe entire frame and attached mechanism may be rotated about the centerpin 4 through an angle of 180, as determined y the stop pin 11, to theproper position for ilignming the other face of the abrasive wheel Asviewed in Fig. 1, the trimmer mechanism may be rotated clockwise aboutthe center pin 4'until the gauge pin 8 comes into engagement with thestop pin 11. The trim ming operation may be repeated on the second faceof the abrasive wheel, thereby providing two working faces adapting itto grind the ad'acent faces of two gear teeth.

t is evident from the foregoing description of the invention that atrimmer mechanism made in accordance therewith is adapted to accuratelytrim the working surfaces of an involute tooth form or diameter. Afurther advantage is obtained by constructing our trimmer mechanism insuch manner that the same trimming member and guiding mechanism may beused to trim each side of the abrasive wheel thereby ensuring exactlythe same contour on each side thereof.

Although we have described a specific embodiment of our invention, itwill be obvious to those skilled in the art that variousmodifi cationsmay be made in the details of construction and the design andproportions of the several cooperating parts of our trimmer mechanismwithout departing from the spirit and scope of the invention as setforth in the appended claims.

We claim as our invention:

1. A trimmer mechanism 4 for abrasive wheels comprising a base member, aframe pivoted on the base member, cylindrical segments pivoted on saidframe about their aligned geometrical axes, said segments having theiraxes disposed at right angles to the pivotal axis of the frame on thebase member, tangent bars mounted to roll upon said seg- 1ments and atrimmer secured to said tangent Mrs. A

2. A trimmer mechanism for abrasive Wheels comprising a base member, aframe supported on said base member, a plurality of cylindrical segmentspivoted on the frame, tangent bars mounted on the segments and adaptedto roll thereon, and a trimmer member pivoted to the tangent bars andadapted to roll with them or to pivot independently of them to trim theabrasive wheel.

3. A trimmer mechanism for abrasive Wheels comprising a base member, aframe carried by the base member, a plurality of cylindrical segmentsmounted .on the frame, tangent bars adapted to roll on the peripheriesof the segments, a trimmer carried by the tangent bars, means forpreventing the tangential displacement of the tangent bars and meanscomprising wheeled carriages mounted on the tangent bars and radiallysupported from the centers of the segments for maintaining the tangentbars in contact with the segments.

4. A trimmer mechanism for abrasive wheels comprlslng a base member, aframe member pivoted on the base member, cylindrical segments havingtheir geometrical axes pivoted upon the frame member at right angles tothe pivotal axis of said frame member, tangent bars mounted upon theperipheries of the cylindrical segments, said bars being free to rollthereon and restrained from tangential-displacement with respectthereto, a trimmer memberpivoted to the tangent bars, means for latchingthe trimmer member to the tangent barsand means for adjusting thepivotal center" of the trimmer member with respect to the tangent bars.

5. In a mechanism foftrimmingjabrasive wheels forgrindingv'g'ear teeth}segment of radius equal to theb cylindrical ase circle radius of thegear-wheel to be ground, a tangent bar adapted to roll upon theperiphery of the segrrfent, atrimmer arm pivoted and latched to saidtangent bar, a trimmer point carried by the trimmer arm, a stop memberfor engaging the tangent bar when the trim mer point is on the peripheryof the base circle, said trimmer arm being adapted to pivot to trim thewheel to an arcuate contour within the base circle.

6. A trimmer mechanism for abrasive Wheels COIHPI'ISIIIg a basemember,-a frame member, cylindrical segments pivoted on the framemember, means for, adjusting the angular position of the frame memberwith respect to the base member, means for adjusting the angularposition of the segments with respect to the frame member, tangent barsdisposed to roll on the segments, a trimmer arm carried by the tangentbars, and a trim mer mounted on the trimmer arm.

7. A trimmer mechanism for. abrasive wheels comprising a cylindricalsegment, a tangent bar mounted to roll upon the periph- -ery of saidsegment, a trimmer arm pivoted trimmer arm pivoted to said tangentbarf'a trimmer carried by the trimmertarm and means for adjusting thepivot center of said trimmer arm relative to the tangent bar in a planeat right angles to the axisof the cylindrical segment.

In testimony whereof, we have hereunto subscribed our names this 16thday of August, 1927 BURTON H. SLOCUM. I JOSEPH A. BOUSLOUGH. LEL AND F.BURNHAM.

